Sear mechanism for a firearm



Jan. 29, 1957 H. E. PINKERTON, JR 2,779,247

SEAR MECHANISM FOR A FIREARM 2 Sheets-Sheet 1 Filed Sept. 28. 1954 IN VEN TOR. Hurry E- Pinkartmr1,.]r

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SEAR MECHANISM FOR A FIREARM 2 Sheets-Sheet 2 Filed Sept. 28 1954 m w w w.

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United States Patent SEAR MECHANISM FOR A FIREARM Harry E. Pinkerton, Jr., Oyster Bay, N. Y., assignor to the United States of America as represented by the Secretary of the Army Application September 28, 1954, Serial No. 459,001

6 Claims. (Cl. 89135) This invention relates to firing mechanisms for automatic firearms and particularly to the sear device thereof.

Itis an object of this invention to provide for firearms having a reciprocating firing pin extension, a rocking sear which is actuatable to the firing pin latch position by the firing pin extension during the overtravel thereof beyond cocked position.

It is another object of this invention to provide a sear device easily adapted to electric solenoid operation.

It is a. further object of this invention to provide means for electrically operating such sear.

It is a specific object of this invention to provide an electrically opera-ted sear mechanism which is simple, compact and rugged in construction and positive in operation.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a longitudinal, partially cross-sectional, fragmentary view of the rear end of a firearm showing the sear actuated to unlatched position by the electric solenoid I and the firing pin extension in firing position;

Fig. 2 is a view similar to Fig. 1 but showing the sear actuated to latched position by the firing pin extension during the overtravel thereof beyond cocked position;

Fig. 3 is a view similar to Figs. 1 and 2 but further fragmentized showing the firing pin extension latched by the sear in cocked position and held therein by a safety; and

Fig. 4 is a reduced, exploded, perspective view of the sear mechanism.

Shown in the figures is a receiver 12, a firing pin extension 14 mounted for reciprocable longitudinal movement therein, a roclcingly mounted sear 16 for latching such firing pin extension in a cocked position and an electrically operated solenoid 18 for rocking such sear to unlatch the firing pin extension.

Extending from the sides of firing pin extension 14 is a pair of oppositely disposed lugs 22 which cooperate with mating longitudinal slideways 24 in receiver 12 to provide slidable movement of such firing pin extension in the receiver and secure such firing pin extension against rotation. Extending forwardly from the rear end of firing pin extension 14 is a bottomed well 26 from which there extends laterally a pair of diametrically opposed longitudinal slots 28. A compressible coil spring 30 is received by well 26 and is bottomed therein and a trans verse pin 32 mounted stationary in receiver 12 is slidably received by slots 28 to permit reciprocable movement of firing pin extension 14 between a forward firing position and a rearward retracted position. The rear end of spring 36 is arranged to bear against pin 32 for biasing firing pin extension 14 to firing position. Firing pin extension 14 is actuated to retracted position by conventional cocking means (not shown).

The top rear portion of firing pin extension 14 is cut away, as noted at 34, to form an upwardly and forwardly extending ramp 36. Extending forwardly from ramp 36 is a planar surface 38 which is terminated at a predetermined distance from such ramp by a recessed forwardly engaging sear catch 40. Sear 16. is provided with a pair Patented Jan. 29, 1957 mounting such sear for rocking movement between a firing pin extension unlatched position and a latched position and is arranged for cooperation withcatch 40 and ramp 36 as hereinafter noted; Lugs 42 which extend beyond the sides of scar 16 are received for rotational movement in a pair of bushings 44 which are threadably mounted in receiver 12. Provided in the portion of scar 16 that extends forwardly from lugs 42 is a depending lip portion 46 which, when the sear is in latch position, engages catch 40 to cook firing pin extension 14 during the initial portion of the return thereof from retracted t-o firing position. The forward end of lip portion 46 inclines upwardly and forwardly, as noted at 41, for a purpose to be hereinafter noted.

The underside of the rear portion of sear 16 is recessed, as noted at 48, to form an upwardly and forwardly inclining cam portion 50 which is arranged to be engageable by ramp 36, when such sear is in the unlatched position, and to cooperate therewith to rock such sear to latch position after sear catch 40 has moved rearwardly past lip portion 46. Recess 48 also provides clearance for planar surface 38 during such-rocking of scar 16 Extending downwardly and forwardly from the rear end of sear 16 is a locking surface 52 which is engageable by the tapered end of a safety 54 slidably mounted in the rear end of receiver 12 for blocking such sear against movement from latch position.

Solenoid 18 includes a substantially U-shaped frame 56 which is mounted in receiver 12 above sear 16, an electric coil 58 which is mounted around a stop portion 57, projecting upwardly from the base of the frame intermediate the leg portion, and is connected by electrical means to controllable electric power source (not shown) and a substantially T-shaped armature 60 responsive to the magnetism of frame 56 by coil 58 when energized. Provided in stop portion 57 is a vertical bore 62 having a non-magnetic bushing 59 received thereby as by press of'approximately centrally located transverse lugs 42 for 2 fit. Threadably mounted in the leg portion of armature 60 is a rod portion 64 which extends through bushing 59 to engage the top of the rear portion of sear 16 for rocking such gear to unlatch position when coil 58 is energized.

Provided through frame 56, above the forward portion of scar 16, is a vertical hole 66 which is counterbored from the top, as noted at 68, and such counterbore is threaded at the top portion to receive a set screw 70. Mounted for slidable movement in hole 66 and counterbore 68 is a plunger 72 having a body portion 74 cooper- .able with such counterb-ore portion and a shaft 76 cooperable with such hole. Shaft 76 is arranged to extend from hole 66 to engage sear 16 forwardly of lugs 42 and a compressible coil spring 78 is installed in counterbore 68 between said screw and body portion 74 to bias plunger 72 downwardly so that shaft 76 can resiliently h-old sear 16 in latched position against the weight of plunger 60 during the return portion of overtravel of firing pin extension 14 when the searis unsupported by firing pin extension 14.

To fire the weapon in which the sear device of this invention is incorporated, the weapon is charged to battery position wherein firing pin extension 14 is latched in cocked position by the engagement of sear catch 40 thereon with lip portion 46 of the sear. Safety 54 is then retracted to unblock sear 16, permitting such sear to be rocked by solenoid 18 when energized by the operator.

When solenoid 18, by means of rod portion 64, presses on the rear portion of sear 16, the front portion thereof rocks upwardly to disengage lip 46 from sear catch 40, thus freeing firing pin extension 14 which is propelled forwardly through the bias of spring 30 to fire the chambered cartridge (notshown). v

During the ensuing recoil 'of the firearm and the cock- 3 ing of firing pin extension cocking means (not shown), sear 16 is rocked to latch position by the camming engagement of ramp 36 on fi ng pin e ension 14 wit cam po t on 0 on such se ve powerin the magnet c pul f s enoid 18,- Sear 1,6 s r tai ed a ch P sit on du ing t e overof in P n xten i n & by he l ng ngag m nt o t sear with planar surface 38. During forward movement of firing pin extension 14, when ramp 36 thereon moves forwardly past cam portion 56, the magnetic pull of solenoidlS rocks sear 16 to unlatch position permitting such firing pin extension to proceed forwardly to firing position. However, if the operator disconnects solenoid 18 from the electrical power source (not shown), to stop the firing of the weapon, spring 78 holds sear 16 in latch position against the weight of plunger 6-,? and thereby lip portion 46 is in position to engage sear catch 40 to sec in Pin x ens on 1 in c c Pos n- It is clearly apparent from the foregoing that sear 16 s ctuate po it ely t la ch p s n by firing P ens on 4, that th sea dev seespec y well u d to le t ic ope ati n y be ng cka v mounted and that the device is simple, compact and rugged in construction.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

1 claim:

1. In a firearm, a firing pin extension longitudinally reciprocable between a firing and a retracted position, a scar mounted for rocking movement between a latched position and an unlatched position, a scar catch on said firing 'pin extension engageable with a lip on said sear for releasably latching said firing pin extension in a cocked position between said firing and retracted positions when said sear is in said latch position, a cam on 1 4 to retracted position by said sear cooperable with a ramp on said firing pin extension during movement thereof from said cocked to said retracted position for rocking said sear to said latch position, and electric means for rocking said sear to said unlatched position.

2. In a firearm, a firing pin extension longitudinally with a ramp on the upper portion of said firing pin extension during movement thereof from said cocked to said retracted position for rocking said sear to said latched position, an electric solenoid cooperable with the rear portion of said sear for rocking thereof to said unlatched position, and a spring-biased plunger mounted in said solenoid for cooperation with the forward end of said sear for resiliently maintaining said sear in said latched position. i

3. 'In a firearm having a receiver, a firing pin extension mounted in the receiver for longitudinal movement between a firing position and a retracted position, said'exnsion ein e sed in he up e p t on. h reo o rm a fo wa d y n a in a c h a d an up rd y and forwardly inclining ramp rearwardly thereof, a scar mounted in the receiver on a pair of lugs for rocking movement between a latched and an unla tched position, said sear being provided with a lip depending from the forward portion thereof for releasably engaging said catch ri g mo ement of a d xtension fr m said is tracted position to a cocked position forwardlythereof and a cam portion on the underside of saidsear rearwardly of said lugs, said cam being engageable by said ramp during movement of said extension from said cocked position to said retracted position for rocking said sear to said latched position, an electric solenoid having a frame and an armature movably responsive to the energizing of said solenoid, said armature being engaged with said sear rearwardly of said lugs for rocking said sear to said unlatched position in response to the energizing of said solenoid, a plunger mounted for slidable vertical movement in said frame for cooperation with said sear forward of said lugs, and spring means for biasing said plunger against said sear to resiliently maintain said sear in said latched position.

4. In a firearm, a firing pin extension reciprocable between a firing and a retracted position, a movable sear for releasably latching said firing pin in a cooked position during movement thereof from the retracted position, an electric solenoid for moving said sear to an unlatched position, and a cam portion on said sear having engagement with a ramp portion on said firing pin extension during movement thereof between the cocked and the retracted positions for moving said sear into position for latching said firing pin extension and said cam portion being disengaged from said ramp portion prior to the return of said firing pin extension to the cooked position to permit actuation of said sear to the unlatched position by said electric solenoid before said firing pin extension reaches the cocked position.

5. In a firearm, a firing pin extension reciprocable be-' tween a firing and a retracted position, a movable sear for releasably latching said firing pin in a cocked position during movement thereof from the retracted position, an electric solenoid for moving said sear to an unlatched position, a cam portion on said sear having engagement with a ramp portion on said firing pin extension during movement thereof between the cooked and the retracted positions for actuating said sear into position for latching said firing pin extension and being disengaged from said ramp. portion prior to the return of said firing pin extension to the cooked position to permit actuation of said sear to the unlatched position by said electric solenoid before said firing pin extension reaches the cocked position, and a planar surface on said firing pin extension to slidingly engage said sear for holding thereof in the latched position during travel of said firing pin extension between the engagement of said cam portion'with said ramp portion and the disengagement thereof.

6. In a firearm, a firing pin extension reciprocable between a firing and a retracted position, a movable sear for releasably latching said firing pin in a cocked position during movement thereof from the retracted position, an electric solenoid for moving said sear to an uulatched position, a cam portion on said sear having engagement with a ramp portion on said firing pin extension during movement thereof between the cooked and the retracted positions for actuating said sear into position for latching said firing pin extension and being disengaged from said rarnp portion prior to the return of said firing pin extension to the cooked position .to permit actuation of said sear to the unlat-ched position by said electric solenoid before said firing pinextension reaches the cocked position, a planar surface on said firing pin extension to slidingly engage said sear for holding thereof in the latched position during travel of said firing pin extension between the engagement of said cam portion with said ramp portion and the disengagement thereof, and a spring-biased plunger for resiliently biasing said sear to said latched position during movement of said firing pin extension between the disengagement of said cam portion from said ramp portion and said cocked position.

References Cited in the file of this patent UNITED STATES PATENTS 2,'642,7 79 Trevaskis June 23, '195 3 

